Question

Based on the gel image and the following information, answer the questions and fill in the table below.

The 100 bp ladder(Fig.1) is used to estimate the length of DNA fragment bands in the gel. Compare the placement of any bands in the sample wells to the ladder bands to determine their approximate lengths. The 356 primers should amplify a 162 bp fragment and the tubulin primers should amplify a 187 bp fragment. 'MolBiol 2003: PGT manual iBook Base Pairs DNA Mass (ng/541) IM | | IIIIIIIII 1.5% TAE agarose gel Figure 1. 100bp ladder

Order of wells: snack 1, 100bp ladder, snack 2, positive control, negative control

Questions:

1. Did the controls work and what do they tell you?

2. Do snack 1 and snack 2 contain the 35S promoter?

3. What conclusion can you draw about the corn-based snacks tested?

Results:

sample	PCR product amplified by 35S primers (~160bp) (yes or no)	PCR product amplified by tubular primers (~190bp) (yes or no)
GM corn
Non-GM corn
Corn based snack 1
Corn based snack 2

Answer 1

Snack 1 Ladder Snack 2 Positive Negative

Tubulin is a gene found in all plants and thus, its amplification provides evidence of DNA preparation.

On the other hand, 35S promoter drives expression of many transgenes. Thus, its amplification provides evidence of transgene.